The present invention relates generally to electrical connectors for use in association with printed circuit boards and, more particularly, to a connector having an improved latching means.
Connectors are used in all types of electronic devices, and are widely used in the computer field. Many computers and other electronic devices have a main printed circuit board, referred to in the art as a "mother" board. Secondary electrical circuits are formed on different substrates as separate printed circuit boards which are added to the mother board, either subsequent to the installation of the mother board in a housing of the device, or prior to the final installation of the mother board into the component housing. These secondary circuits are typically designed to improve the performance of the device and are referred to in the art as "daughter" boards.
A connector is typically used in the computer art to connect a daughter board to the mother board. To provide an effective connection, connectors include a number of conventional features such as a longitudinal slot which receives an edge of the daughter board and a plurality of electrical terminals disposed in the slot in alignment with a like plurality of electrical contact pads arranged along the edge of the daughter board. The connection is effected along this edge of the daughter boards, and accordingly, daughter boards are often descriptively referred to as "edge cards".
The connector terminals may typically include contact portions located in the connector housing which provide electrical contact between the connector and the edge card. The terminals also may include tail portions which extend out of the connector housing and which are received within corresponding holes in the mother board in order to provide a connection between the circuit(s) on the edge cards and the mother board. The electronics art and especially the computer art have noticed the desire of consumers for smaller computer devices as evidenced by the increase in popularity of "laptop" and "sub-notebook" computers, as well as smaller size desktop computers. In order to reduce space, connectors have been developed which are smaller than past connectors, and having a closer profile to the mother board. Sometimes, these low profile, or right angle connectors are designed in order to position the daughter board in a horizontal orientation, parallel to the mother board surface, rather than vertical and perpendicular to the mother board surface.
Right angle connectors are often used to provide electrical connections between memory modules, known in the art as either SIMMs (single in-line memory modules) or DIMMs (dual in-line memory modules). There is a primary difference between a SIMM and a DIMM which highlights the need for even more reliable connectors used with DIMMs. SIMMs typically contain their electrical contact pads along the opposing edges of the engagement edge of the SIMM in a redundant manner, i.e., a contact pad on one side of the SIMM has a corresponding contact pad disposed on the other side of the SIMM and the two contact pads are electrically connected to the same circuit.
The structure of a DIMM is different because each electrical contact pad on the opposing sides of the DIMM leads to a different circuit and, therefore requires a higher degree of certainty of contact between the connector terminal contact portions and the DIMM contact pads than a SIMM because of the lack of redundancy. If a break in contact occurs, disengagement of the connection established in the connector between the edge card contact pads and the terminal contact portions may result, potentially causing a computer failure.
Latching mechanisms have been developed for connectors in order to retain edge cards in place in the connector housing. Latching mechanisms for SIMMS are typically either directly formed in the structure of the connector housing at opposing ends, or they may be separately formed and inserted into the connector housing. These latching mechanisms may include different configurations for contacting the edge card and for retaining it in place within the connector housing. Examples of insertable latches are described in U.S. Pat. No. 4,995,825 issued Feb. 26, 1991 and U.S. Pat. No. 5,094,624, issued Mar. 10, 1992. The latches described in these patents are stamped and formed from a metal strip and are used in "insert and rotate" connectors wherein the engagement edge of the edge card is initially inserted into the connector slot and subsequently rotated to a second position in the connector slot into engagement with the terminals.
Another insert and rotate connector having a latching mechanism is described in European Patent Publication No. 0632542, published Jan. 4, 1994. The latching mechanism described in this patent includes latching members having a pair of wide shoulders which engage the ends of a circuit card and a tongue which is folded over the shoulders in order to contact the circuit card. Although these shoulders are illustrated as extending into opposing recesses positioned in the ends of an edge card, the entire latch arm is formed by stamping and forming the latching members over the shoulders. The tolerances in forming these latch members are not as accurate as may be obtained through blanking.
Small outline DIMM connectors of the type shown in European Patent Publication No. 0632542 are small in size and shape, and the latch members are likewise small. The difficultly in accurately stamping and forming a latch member increases as the overall size of the latch member decreases. In order to position the edge card accurately in the connector, such small outline DIMMs typically utilize a pair of notches or other style reentrant portions formed on the opposite ends of the edge card which engage an opposing surface of a latch member. The relatively small size of a DIMM and its lack of electrical redundancy requires that the latch member reliably hold the DIMM in place within the connector. It is desirable to engage the DIMM with the connector in a manner which will ensure accurate alignment and connection between the terminals and edge card contact pads and resist shock loading.
Accordingly, a need exists for a connector in which the edge card is inserted and rotated into position wherein the connector has a reliable latching mechanism which retains the edge card in place within the connector.